The invention concerns a device for connection to a wireless network, wherein the device is connected to at least one other network. The invention may be used for connecting, for example, an Ethernet and/or a USB network to a wireless network such as IEEE 802.11.
In a centralized wireless network, e.g. conforming to IEEE 802.11 (BSS), a device called Access Point (AP) centralizes certain management functions, in particular medium access and data unit delivery between stations.
In IEEE 802.11, the Access Point may comprise a bridge function, in order to allow the connection of the wireless network to another network of any type, e.g. a local area network (LAN), for example an Ethernet LAN or another network of the IEEE 802.x type. IEEE 802.11 refers to this function as Distribution System Service (DSS), as described in sections 5.2 to 5.4 of the document ISO/IEC 8802-11, 1st edition, 1999.
In HiperLAN2, another centralized wireless network, the model is more generic in the sense that it supports different types of core networks (and not only 802.x networks), as described in the HiperLAN2 system overview (ETSI TR 101 683). While mostly focused on Ethernet core networks (where the architecture is homogeneous with 802.11 DS (Distribution System)), the relevant document is the HiperLan2 Ethernet SSCS TS (ETSI TS 101 493 part 2).
Bridging functions in general are described e.g. in ISO/IEC 15802-3:1998 (also known as ANSI/IEEE Std 802.1D). A bridge as defined in this document possesses two or more IEEE 802.x compliant MAC interfaces. In order to avoid passing useless data, the bridge sets up a filtering table for each MAC interface. Each table is fed with source MAC addresses of packets detected on the corresponding interface. The bridge does not forward packets with destination addresses it spots in the filtering table of the interface on which the packets were detected. An ageing process is applied to the filtering tables in the sense that source addresses that are not detected for a certain time are removed from the tables.
FIG. 1 illustrates a prior art network comprising three wireless basic service set (BSS) networks comprising a number of stations (STA) connected through their respective access points (AP) to an Ethernet wired network.
Since only one Access Point is allowed per BSS, it is impossible to use a wireless network of this type to act as a backbone for connecting other networks.